Previous Definition (Better)
As with seam welding and spot welding, projection welding is used to join two overlapping sheets of relatively thin metal. The process involves pressing a number of 'dimples' in one of the plates, welding the two plates together at the same time.
The method can also be used for welding metal sheet to the ends of bars, rods or pipes, or for welding nuts to sheets. Wire grids (i.e. the crossing points of the wires) are also particularly suitable for projection welding.
An advantage of the process, relative to spot welding, is that there is less wear and tear on the electrodes due to the greater contact area.
(Weman K., Welding processes handbook, p. 83)
New Definition(Joining Method)
Refer to Fig.
7.3. It is in effect, a form of multi-spot welding in which a number of welds
are made simultaneously.
— The pieces to be welded are arranged between two
flat electrodes which exert pressure as the current flows.
— The
projections, and the areas with which they make contact, are raised to welding
heat and are joined by the pressure exerted by the electrodes.
— The
projections are flattened during the welding.
Applications :
The process is used chiefly to join pressings together since it is relatively
simple to make the press-tools so that the projections are produced during the main
forming operation in the press.
— The materials like brass and aluminium cannot be projection
welded satisfactorily.
• The same principle is used in the cross welding of a
number of wires or rods to make a mesh.
(Rajput, R. K. A Textbook of Manufacturing Technology:
(manufacturing Processes), p.299)
No comments:
Post a Comment